U.S. patent number 4,377,329 [Application Number 06/124,941] was granted by the patent office on 1983-03-22 for contact lens or the like.
Invention is credited to Stanley Poler.
United States Patent |
4,377,329 |
Poler |
March 22, 1983 |
Contact lens or the like
Abstract
The invention contemplates improved extraocular-lens structures
for contact with the cornea of a human eye, to be worn in place of
spectacles. The construction features a lens element of requisite
prescription power but of diameter which substantially equals or
only slightly exceeds the fully dilated pupil size of the wearer,
and fenestrated haptic structure engaged to the lens extends
radially outwardly and is so thin and axially compliant as to be
self-conforming to the curvature of the cornea and to effectively
adhere thereto, thus stabilizing the lens for retention of its
position on the optical axis of the eye.
Inventors: |
Poler; Stanley (New York,
NY) |
Family
ID: |
22417525 |
Appl.
No.: |
06/124,941 |
Filed: |
February 26, 1980 |
Current U.S.
Class: |
351/159.02;
D16/101 |
Current CPC
Class: |
G02C
7/048 (20130101); G02C 7/049 (20130101); G02C
7/047 (20130101); G02C 2202/16 (20130101) |
Current International
Class: |
G02C
7/04 (20060101); G02C 007/04 () |
Field of
Search: |
;351/16H,16R,161,177
;3/13,13A |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
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|
|
908135 |
|
Aug 1945 |
|
FR |
|
946877 |
|
Dec 1948 |
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FR |
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Primary Examiner: Corbin; John K.
Assistant Examiner: Sugarman; Scott J.
Attorney, Agent or Firm: Hopgood, Calimafde, Kalil,
Blaustein & Judlowe
Claims
What is claimed is:
1. A contact lens assembly adapted for self-adherent removable
mounting to the cornea of an eye, comprising a circular lens
element, and haptic means peripherally engaging and mounting said
lens element, said haptic means being of sheet material including
integrally formed axially compliant radially outward foot
formations extending outward of said lens element at angularly
spaced locations, said foot formations being substantially
fenestrated and being of such compliant action as to bendably
deform in continuous smooth conformance to the surface curvature of
the cornea and to adhere thereto solely through contact with
natural moisture of the surface of the cornea.
2. The lens assembly of claim 1, in which the locus of outer ends
of said foot formations, in flattened state, is a generally
circular perimeter of minimum diametral span which is at least no
greater than the span of the substantially great-circle arc between
conjunctiva limits of the eye.
3. The lens assembly of claim 1, in which the locus of outer ends
of said foot formations, in flattened state, is a generally
circular perimeter of minimum diametral span in the range 9 to 15
mm.
4. The lens assembly of claim 1, in which said haptic is of
fenestrated sheet material, whereby the effective surface area of
said haptic is reduced by fenestration radially outside said lens
element, the locus of outer ends of said foot formations being a
generally circular perimeter, the fenestrated area within said
locus being substantially greater than said effective surface
area.
5. The lens assembly of claim 4, in which the fenestrated area
within said locus is at least four times the end area of said lens
element.
6. The lens assembly of claim 1, in which the diameter of said lens
element is in the range 5 to 7 mm.
7. The lens assembly of claim 1, in which the diameter of said lens
element is no greater than substantially 6 mm.
8. The lens assembly of claim 1, in which the diameter of said lens
element is no greater than substantially 5 mm.
9. The lens assembly of claim 1, in which said lens element is of
optically finished glass.
10. The lens assembly of claim 9, in which said haptic means is of
plastic.
11. The lens assembly of claim 9, in which said haptic means is of
glass.
12. The lens assembly of claim 1, in which said lens element is of
a first plastic material, and in which said haptic means is of a
second plastic material.
13. The lens assembly of claim 1, in which said haptic means
comprises two pieces of transparent sheet material laminated to
opposite axial sides of said lens element and laminated to each
other at regions radially outside said lens element.
14. The lens assembly of claim 1, in which said haptic means
comprises two pieces of sheet material having registering circular
apertures of diameter less than the outer diameter of said lens
element, said sheet-material pieces being in lapped engagement with
opposite axial sides of said lens element at the rim region thereof
and being laminated to each other at regions radially outside said
lens element.
15. The lens assembly of claim 1, in which said haptic means
comprises a single piece of sheet material having a central
aperture at which the periphery of said lens element is secured to
said sheet material.
16. The lens assembly of claim 1, in which said lens element is of
optically finished glass and said haptic means is of transparent
glass sheet bonded to the posterior surface of said lens
element.
17. The lens assembly of any one of claims 13, 14, 15 and 16, in
which said haptic means in the region radially outside said lens
element is fenestrated to an area extent which exceeds the
remaining effective haptic area radially outside said lens element,
and in which said remaining effective haptic area is at least twice
the area of said lens element.
18. The lens assembly of claim 13 or claim 14, in which said haptic
mean is characterized by multiple fenestrations in the region
radially outside said lens element, the minimum width of all
fenestrations in said region being substantially greater than the
overall laminated thickness of said two pieces of sheet
material.
19. The lens assembly of claim 1, in which said foot formations are
four in number, at substantially equal angular spacing, each foot
formation comprising angularly spaced generally radial leg elements
integrally interconnected at their radially outer ends by a
transverse bridge element.
20. The lens assembly of claim 19, in which said bridge element is
generally arcuate about the central axis of said lens element.
21. The lens assembly of claim 19, in which the radial extent of
one diametrically opposed pair of foot formations exceeds that of
the other pair, thereby recognizably establishing a major-axis
orientation that is characteristic of said haptic means.
22. The lens assembly of claim 21, in which said lens element is of
optically finished glass, with an astigmatism-corrective axis
having a predetermined angular orientation with respect to the
characteristic major-axis orientation of said haptic means.
23. The lens assembly of claim 19, in which each of said leg
elements is slotted along its length, the slot width being in
excess of the thickness of said haptic means.
24. The lens assembly of claim 19, in which each said bridge
element is slotted along its length, the slot width being in excess
of the thickness of said haptic means.
25. The lens assembly of claim 9, in which said optically finished
glass is photochromic.
26. The lens assembly of claim 1, in which said haptic means
includes an annular region radially outside said lens element and
of maximum diameter corresponding to the maximum diameter of the
iris, said haptic means in said annular region being effectively
opaque and characterized by external appearance decor and coloring
to suit the eye of a patient and to simulate the iris of the
patient, said foot formations extending radially outside said
annular region.
27. The lens assembly of claim 26, in which said annular region is
characterized by foraminous apertures of effective diameter less
than substantially 0.005 inch and at least as great as the
thickness of said annular region.
28. The lens assembly of claim 1, in which said haptic means is of
thickness at least no greater than substantially 0.002 inch.
29. The lens assembly of claim 1, in which maximum thickness is at
least no greater than substantially 0.006 inch (0.15 mm).
30. The lens assembly of claim 14, in which said sheet-material
pieces are laminated to said lens element at lapped engagement with
said rim region.
31. The lens assembly of claim 13 or claim 14, in which the
respective sheet pieces are of different materials, the anterior
piece being of lower inherent friction coefficient than the
posterior piece.
32. The lens assembly of claim 13 or claim 14, in which the
posterior surface of the posterior sheet piece is characterized by
greater surface roughness than that of the anterior surface of the
anterior sheet piece.
33. The lens assembly of claim 1, in which said haptic means
integrally includes a peripherally continuous rim, said foot
formations terminating at said rim.
Description
BACKGROUND OF THE INVENTION
This invention relates particularly to extraocular lens structures
for contact application to the cornea, for wear in place of
spectacles.
Conventional contact lenses, be they of the hard or soft variety,
are circular, of 12 to 14 mm diameter, and thus cover a relatively
large area, approximating the area defined by the perimeter of the
iris. They are larger than optically necessary because the only
light rays they need accommodate are those permitted by the pupil,
and their relatively large area is a source of discomfort because
fluid on the cornea is thereby precluded natural flow and
circulation; as a consequence, the wearer of contact lenses must
accustom himself to relatively frequent removal, cleaning and
replacement of his lenses. But if the conventional contact lens
were any smaller, it would be virtually incapable of manipulation
by the wearer, and it would also be prone to move off-axis, over
the corneal surface. Furthermore, liquid and gas-permeable plastics
have recently been used, but lenses of such materials tend to build
enzyme deposits and present difficulties in regard to cleaning and
sterilization.
As far as I am aware, glass has been foreclosed as a contact-lens
material, due to its high density and fragility compared to that of
plastic materials. And the manufacture of contact lenses has
involved plastic-molding techniques where prescription curvatures
are derived from a molding cavity, or by lathe-cutting, i.e., they
are not expressly not ground into the lens itself. And being
circular, there is no way that astigmatism can be corrected through
conventional contact lenses because there is no way of identifying
orientation parameters of the astigmatism.
BRIEF STATEMENT OF THE INVENTION
It is an object to provide an improved extraocular or contact-lens
construction.
It is a specific object to provide such a construction wherein the
lens element itself may be of substantially smaller size,
consistent essentially only with its optical requirements, and
wherein haptic structure engaged to the lens element provides
stabilized positioning for the lens element.
Another specific object is to meet the above objects with structure
which is readily self-adapting to the curvature of the cornea.
It is also a specific object to provide structure meeting the above
objects and permitting the employment of optically finished glass
as the material of the lens element.
A further object is to provide a contact-lens construction
inherently capable of supplying astigmatism correction for the
wearer.
Still another object is to provide a contact-lens structure of the
character indicated that can be cleaned and sterilized by boiling
in water or by autoclaving.
It is a further specific object to provide protective structure in
a contact lens whereby glass may be safely used as the optical
element.
A general object is to meet the above objects with relatively
simple structure which lends itself to quantity and precision
manufacture, which inherently provides improved comfort to the
wearer, and which involves substantially reduced demands for
removal, cleaning and replacement.
The foregoing and the other objects and features of the invention
are achieved in contact-lens constructions (a) wherein the lens
element is of substantially reduced diameter (e.g., 5 to 6 mm), and
is thus essentially only of the size required to serve a fully
dilated pupil and (b) wherein fenestrated compliant haptic
structure engages the lens element and adheres to the wet surface
of the cornea for stabilized support of the lens element. The
result is a much lighter-weight article, of less bulk than
conventional contact lenses, and permitting the use of optically
finished glass for the lens element.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be illustratively described in conjunction with
the accompanying drawings, in which:
FIG. 1 is a simplified front-elevation view of a human eye to which
contact-lens structure of the invention has been applied;
FIG. 2 is an enlarged view of the lens structure of FIG. 1 to show
haptic detail;
FIG. 3 is a side-elevation view of the structure of FIG. 2;
FIG. 4 is a view similar to FIG. 3 but with the separate parts in
exploded relation;
FIG. 5 is a view similar to FIG. 4 to show a modification;
FIG. 6 is a sectional view, taken at 6--6 of FIG. 2 and on a
further-enlarged scale;
FIG. 7 is a view similar to FIG. 2, to show a modification;
FIGS. 8 and 8A are fragmentary views, otherwise similar to FIGS. 7
and 2, respectively, to show further modification;
FIGS. 9 and 9A are similar to FIGS. 8 and 8A, to show further
modification; and
FIGS. 10 and 11 are views similar to FIGS. 3 and 4, respectively,
to show still further modification.
DETAILED DESCRIPTION OF THE INVENTION
In the form of FIGS. 1 to 4, the invention is shown in application
to an extraocular or contact-lens assembly comprising a central
lens element 10 which may be of molded plastic, but which is
preferably of optically finished glass, ground to prescription
curvature (e.g., plano-convex or meniscus) and of outside diameter
D.sub.1 which equals or slightly exceeds the diameter of the fully
dilated pupil of a human eye. As is clear from FIG. 1, the diameter
D.sub.1 is very much less than the diameter D.sub.2 of the iris 12
of the eye 11. Generally speaking, the diameter D.sub.1, is in the
range 5 to 6 mm, and the diameter D.sub.2 is in the range of 12 to
14 mm, the latter being the diameter of a conventional contact
lens.
Fixed to and centrally supporting the lens element 10 is a haptic
13 of much larger included area than the lens element 10. Haptic 13
comprises two thin sheets 14-15 of plastic material laminated to
the front and back surfaces of lens element 10, and to each other
in regions radially outside element 10; in these outer regions,
haptic 13 is characterized by very substantial fenestration,
meaning that the structure is primarily "open", for normal air or
"breathing" exposure of the surface of the cornea. Such
fenestration may be by photographically delineated milling, before
or after lamination of the sheets 14-15 to each other, relying upon
such chemical-etching, plasma and other milling techniques as are
described for intraocular-lens haptics, in my U.S. Pat. No.
4,080,709.
More specifically, each of the sheets of haptic 13 is seen to be of
generally oval or elliptical outer contour and to comprise four
radially outward foot formations, there being a first larger pair
16-17 on the major axis and a second shorter pair 18-19 on the
minor axis. It is intended that these foot formations be very
compliant in the axial direction, to render them self-conforming to
the surface of the cornea. Each foot formation, taking formation 16
as typical, comprises angularly spaced outer legs 20 and a central
leg 21 integrally connecting an inner hub portion 22 to an outer
bridge portion 23; and intermediate their points of interconnection
all these elemental areas are slotted, as at 24, to render them
even more self-conforming to the surface of the cornea. The sheets
14-15 should be selected for autoclavability and may be of 1-mil or
0.5 mil material, suitably nylon, high-density polyethylene,
Mylar*, Teflon*, polyethersulfone, sheet silicone, or H.E.M.A.,
meaning that in the elemental areas 20-21-22-23, the haptic is of
thickness T.sub.1 (FIG. 6) in the range of 1 to 2 mils; the width
W.sub.1 of each of these areas is typically in the order of 10
mils, and slot widths W.sub.2 are in the order of 3 mils. The
overall dimensions of the haptic blank may suitably be 16 mm.
(major axis) by 12 mm. (minor axis). Bonding of the plastic sheets
14-15 to each other may be by suitable ultrasonic, heating or
cementing techniques, as applicable.
Prior to application to the cornea, the foot formations 16-17-18-19
are so axially weak ("floppy") as to be apparently useless as
supports for the associated lens element 10. However, once the
central lens-bearing region is placed over the pupil, the adjacent
floppy regions are drawn, by a self-wetting action akin to surface
tension and/or capillary attraction (in the context of surface
moisture on the cornea) to lie down on the cornea in conformance to
locally adjacent curvature of the cornea. In addition to rendering
the elemental areas 20-21-22-23 more compliant, the slotted regions
(24) thereof achieve a pump-like coaction with surface liquid on
the cornea, with the result that surface liquid is locally
displaced and drawn into and through the slotted regions (24), and
essentially all haptic area radially outside the lens element 10
has an affinity for the cornea region to which it has "attached"
itself by self-wetting. Thus, the relatively narrow and slotted
nature of areas 20-21-22-23 promotes displacement of surface
liquid, with the attendant benefit of cleaning and lubricating
action, particularly when blinking the eyelid over the installed
structure. And the 1 to 2-mil haptic thickness encountered by a
blinking eyelid is inconsequential, while the lens element remains
sufficiently anchored in its installed eye-axis position, it being
further noted that, as a result of using the indicated milling
techniques, all edges of the haptic formations are smoothly rounded
and therefore not a source of irritation. The anchoring effect is
enhanced by providing a mildly roughened surface (as by etching) on
the posterior side of the haptic areas 20-21-22-23, and the
smoothness of eyelid action is enhanced by providing a smooth
anterior surface of the haptic; the roughened surface will have
been created prior to milling and will have a dull or matte
appearance, and the smooth surface will be shiny, thus enabling
ready identification of the front and back surfaces of the
assembly.
In the form of FIGS. 1 to 4, the sheets 14-15 continuously and
intimately cover the respective front and back surfaces of lens
element 10. The selected plastic material of sheets 14-15 must
therefore be for their transparency, and as noted previously,
reliance is upon the lens element 10 for optical properties.
Generally, it may be observed that use of plastic material for lens
element 10 means an index of refraction substantially less than
that of glass. Therefore, production of plastic lens elements 10
will mean greater curvature (shorter radii), and therefore greater
lens thickness, then for a glass lens element 10 of the same
diopter specification. In the case of the glass lens element 10,
optical glasses are commercially available with various indices of
refraction in the range 1.5 to 2.0, and I find that by grinding all
lens elements 10 (as optically finished plano-convex elements),
with the same single radius of curvature (e.g., 300-mm radius), a
full range of prescribable diopter powers (at quarter-diopter
increments, up to 10 diopters) is available merely by choice of the
glass for its particular index of refraction; a single set of
lens-grinding tools which grind to a single radius of curvature may
be used to implement the foregoing technique involving glasses with
different indices of refraction. A similar single-radius approach
in grinding negative-lens surfaces will also serve a wide range of
diopter prescriptions, through appropriate selection of a
particular glass for its index of refraction, as by using a single
set of lens-grinding tools which grind to a single radius of
curvature. Further, because glass elements 10 may be finished with
prescribable grinding eccentricity, astigmatism correction can be
provided, the lens element being oriented with its
astigmatic-correction axis rotationally displaced to a prescribed
angular orientation with respect to, say, the major axis 16-17 upon
assembly to and lamination with the haptic parts 14-15; the exposed
dull vs. shiny surfaces of the haptic, being recognizably exposed,
enable the user to make sure that his installed lens (major axis
horizontal, shiny side facing forward) will always be so installed
in his eye as to avoid astigmatic ambiguity.
FIG. 5 illustrates a modification wherein each of the haptic sheets
14'-15' is formed with a central aperture of diameter D.sub.2, to
enable peripheral overlap with the rim of lens element 10;
lamination of the sheets 14'-15' and their substantial fenestration
radially outside lens element 10 is otherwise as described for
FIGS. 1 to 4. The diameter D.sub.2 is illustratively 4.5 to 5 mm,
to allow such peripheral overlap to the radial extent of 0.5 to
0.75 mm, for the case of a 6-mm diameter D.sub.1 of lens element
10.
FIG. 7 depicts an alternative construction, particularly suited to
eyes for which no astigmatism is to be corrected. The only
significant difference in FIG. 7 is that the outer perimeter of the
haptic 30 thereof is generally circular. In other words, all foot
formations 31-32-33-34 are alike, and preferably comprise slotted
elemental hub, foot, and bridge areas corresponding to areas
20-21-22-23 of FIG. 2.
FIGS. 8 and 8A respectively illustrate circular and elliptically
contoured versions of a modified version of the invention,
particularly suited to the a-tonic iris, i.e., an eye having no
iris or a damaged iris. One or both of the sheets which comprise
the haptic 40 (40') is characterized by an opaque annular region 41
(41') extending from the lens-lapping inner diameter D.sub.2 to an
outer diameter D.sub.3 to match the person's other-eye iris
diameter. Foot formations 43-44 (43'-44') extend radially outward
of the hub region of lens element retention, but the major open
fenestration is radially outside the annulus 41 (41'), the "opaque"
region 41 (41') being desirably foraminated with apertures of
diameter preferably less than substantially 0.005 inch and at least
as great as the thickness of region 41 (41'), to permit "breathing"
action of the corneal surface covered thereby. Desirably, the
"opaque" region is so finished as to color and design as to create
the appearance of a normal iris in the afflicted eye.
FIGS. 9 and 9A illustrate modification of the respective circular
and elliptical embodiments of FIGS. 7 and 2, wherein the haptic 50
(50') is peripherally continuously a circle or an ellipse or oval.
Slotting of elemental areas of haptics 50 (50') is again preferred,
as described for FIG. 2. The floppy nature of the continous
periphery of both haptics 50 (50') enables continuous intimate
attraction to the cornea surface in the manner described for FIGS.
1 to 4, and the plurality of axially compliant radial leg elements
51 (52-53) is preferably at least three, being shown as four, for
both FIGS. 9 and 9A.
FIGS. 10 and 10A are directed to an all-glass embodiment of the
invention wherein the lens element 10 is an optically finished
element, shown as plano-convex and with a cylindrical rim of
thickness T.sub.2 in the range 1 to 3 mils, preferably
substantially 2 mils. The flat posterior side of lens element 10 is
mounted, as by fusing or by a suitable cement, to the central
region of a sheet glass haptic 60 of thickness in the range 0.5 to
1.5 mils, preferably 1 mil. Fenestration is provided in the haptic
region external to lens element 10, in the manner discussed above
for the forms of FIGS. 2 and 7, 9 and 9A, as the case may be. The
glass haptic 60 is thus substantially as floppy as its plastic
counterpart, but it has the advantage of being less susceptible to
bacteria-growth phenomena, and therefore less likely or less often
to require removal for cleaning and sterilization; its ultimately
flexed curvature in adaptation to the cornea is suggested by dashed
lines 60.
The described embodiments of the invention will be seen to achieve
all stated objects. Importantly, the invention brings light weight
and substantially reduced bulk and surface area to the contact-lens
art, plus the inherent capability of providing optically finished
glass lens elements, with astigmatic correction, if needed;
further, photochromic glass at 10 provides a hitherto unavailable
feature in a contact lens configuration. Fenestration areas are
substantial, radially outside the supported lens element 10, being
preferably at least four times the end area of the lens element,
such area being taken as within effective perimeter limits of the
geometric circular or oval (elliptical) contour to which the foot
formations are tangent. Except for the "opaque" annulus 41 (41') of
FIGS. 8 and 8A, all other haptic regions and materials are
preferably clear and transparent, foot formations of such haptic
regions being effectively invisible to the eye of an observer.
Not only does the invention bring above-noted benefits of optically
finished glass to the contact-lens art, but an important safety
factor is also provided. In embodiments involving plastic-sheet
haptics, the plastic sheets of the haptic fully enclose and support
the lens element in at least the region of its rim; in other words,
it is at least the most delicate and fracturable part of the lens
which is protected by such plastic-sheet enclosure. In glass-haptic
situations as described in connection with FIGS. 10 and 10A, the
haptic sheet 60, being bonded to lens element 10 over its full
area, provides reinforcement to the otherwise more fracturable rim
region of the lens element 10; in the event that lens element 10 is
a meniscus lens, the haptic sheet 60 is preferably centrally open
to the diameter D.sub.2 (see FIG. 5), but there will be an annular
overlap (D.sub.1, minus D.sub.2) within which sheet 60 and lens 10
are bonded, thus providing lens-rim reinforcement, in addition to
the described support and positioning functions of the haptic.
It should be further observed that although curvatures and diopter
ranges have been mentioned by way of illustration, these ranges are
in no sense by way of limiting the invention. For example, the
invention will be seen to have application to aphakic patients,
i.e., to those whose cataracted natural lens has been surgically
removed but for whom an external lens, rather than an implanted
intraocular lens, has been prescribed. Such lenses may be of the
structure, nature and combinations herein described, but with a
stronger finished optical element 10, e.g., having power in the
order of 10 or more diopters. When such stronger lenses are of
glass, the thickness of the lens element 10 per se will still be
very much less than for a conventional contact lens prescribed for
the same situation.
While the invention has been described in detail for preferred
forms shown, it will be understood that modifications may be made
without departure from the claimed scope of the invention. For
example, the technique of retaining an optical element by and
between laminated plastic sheets which become the haptic lends
itself to intraocular-lens application, so that for example, a
configuration as in FIG. 7, and with three or more foot formations
within an outer circular locus of 12 to 14-mm diameter may serve
well for anterior-chamber implantation, relying upon the foot
formations to develop stabilizing support at the scleral ridge
(adjacent the base of the iris). Of course, in that event, the
haptic sheets should provide a more stiff radial-support action, in
that they stand without contact analogous to the described
cornea-adherent extraocular applications herein; thus, for
intraocular application the overall haptic thickness T.sub.1 is
preferably about 10 mils, and of course lens curvatures will be of
shorter radius in view of the vitreous-humor environment in which
such lenses must function.
* * * * *